Fluorescent lamps have been a very successful light source. They are used on a huge scale. In fact more than 60% of the artificial light is generated by fluorescent lamps today. However, in recent years LED lighting technology has been rapidly developed and replacement of fluorescent lamps by LED replacement lamps becomes attractive because of the high efficiency of LED lamps and their long life.
There are various LED replacement lamps on the market today. An example of such a LED replacement lamp is disclosed in US 2011121756.
For proper operation, most of these replacement lamps require a rewiring of the fluorescent lamp fixture, by taking out the ballast or bypassing it. However, the easiest way to upgrade a fluorescent lamp luminaire is by taking out the fluorescent lamp and replacing it with a LED replacement lamp. In that case no rewiring or opening of the fixture is required.
LEDs are more efficient than fluorescent lamps (higher lumen/Watt). Furthermore, the LEDs comprised in a LED replacement tube shine most of their light downwards so that a LED replacement lamp has a much higher optical efficiency than a fluorescent lamp shining its light all around the tube. As a consequence, in case for instance a four feet fluorescent lamp with a nominal power of 32 Watt is replaced by a LED replacement lamp generating the same amount of light on a desk situated under it, the power consumption of the LED replacement lamp is approximately 20-25 Watt, based on the present efficiency of the LEDs. The power consumption of the LED replacement lamp will further decrease when the efficiency of the LEDs increases in the future. Handling this difference in the power consumed by the LED replacement lamp and the power consumed by the fluorescent lamp that the fluorescent lamp diver was designed for, is a key challenge in LED replacement lamp design.
In the LED replacement lamp disclosed in US 2011121756 the LED replacement lamp is equipped with rectifiers and LC filters to generate a DC-current out of the high frequency voltage supplied by the fluorescent lamp ballast. However, US 2011121756 does not disclose any features to ensure that the power consumed by the LED replacement lamp is lower than the power supplied by the high frequency fluorescent lamp ballast.